The invention relates to a microwave circuit arrangement according to claim 1 and its use in mobile telephones or mobile radio transceivers.
It is desirable to operate mobile-radio and mobile-telephone systems not only outside but also in the interior of vehicles. In the interior of the vehicles the transmitting and receiving sections of the mobile-radio and mobile-telephone systems are not connected to the built-in antenna but to an external antenna fitted to the vehicle. Semiconductor switching circuits arranged within the mobile-radio and mobile-telephone systems are usually used for changing over the connection between transmitter, receiver, antenna 1 (external) and antenna 2 (internal).
The publication IEEE Journal of Solid-State Circuits, Vol. 31, No. 10, October 1996 describes an antenna changeover for high-power microwaves. The arrangement, which is constructed monolithically with the aid of GaAs JFET semiconductor switching elements, enables the connection of a transmitter (Tx) to an external antenna and an internal antenna, or the connection of a receiver (Rx) to one of said antennas. In the case of the switching arrangement described, two states can be switched, in the case of each of which an input is connected to an output. By way of example, if the internal antenna built into the device is connected to the receiver, the external antenna is connected to the transmitter. In the second switching state, the built-in antenna is connected to the transmitter and the external antenna is connected to the sreceiver. Two input signals are required for controlling these two states (2 bits).
The object of the present invention is to provide an antenna changeover circuit arrangement which enables a changeover between transmitter/receiver and antenna 1/antenna 2 and at the same time, affords a possibility for changing over the mobile-radio and mobile-telephone system between two frequency bands (e.g. between GSM mode and PCN mode in dual-band mobile telephones).
The invention relates to a microwave circuit arrangement in accordance with claim 1.
The driving of the semiconductor switching elements by alteration of the potential at drain and source in accordance with the invention makes it possible to reduce the drive lines required for coding the switching states by comparison with exclusive driving by alteration of the potential at the gates.
Examples of semiconductor switching elements which can be used in accordance with the invention are field effect transistors known per se, such as MESFETs, JFETs or MOSFETs. Those types which are suitable for switching high power levels are preferred. The control voltage of the semiconductor switching elements is advantageously in the region of less than 5 V, in particular 3 V.
It is possible for the circuit according to the invention to be constructed from discrete components. However, all of the semiconductor switching elements are preferably integrated on a circuit, for example in the form of a Monolithic Microwave Circuit (MMIC). The chip area to which the circuit according to the invention can be applied is preferably smaller than 1200xc3x971200 xcexcm2. It is particularly preferred for the chip area to be smaller than 800xc3x97800 xcexcm2.
The integrated circuit is preferably accommodated in a chip carrier housing. The connections can then be routed to the outside in a customary manner via bonding.
The driving of the switching elements in the circuit by changing potential can be effected by means of control lines. If a control line is used to switch a specific function, additional circuit sections with additional coding logic are unnecessary. It is therefore preferred for there to be no circuit sections of hybrid construction present in the circuit arrangement according to the invention.
The circuit according to the invention is preferably operated with an operating voltage. In other words, there is only one operating or supply voltage, with a constant value, applied to the circuit. Additional supply voltages are not required.
The circuit according to the invention can be used quite generally for changing over between signal sources in the microwave range (preferably from 500 to 2500 MHz). It is preferred, however, for the circuit according to the invention to be connected to at least two transmitting apparatuses and at least two receiving apparatuses.
The circuit according to the invention can be used for antenna changeover in dual-band mobile telephones with two transmitting and receiving sections in each case. It is thus preferred for the circuit to be connected to two or more transmitters and to two or more receivers, in which case the transmitters and receivers respectively differ in that they operate on different frequency bands.
The circuit according to the invention can be utilized for changing over between transmitters and receivers onto one antenna. It is preferred for the circuit to be connected to at least two antennas.
A further possibility is changeover between an internal antenna and an external antenna. Therefore, the circuit according to the invention is preferably connected to two or more antennas.
In a particularly preferred manner, two transmitters, two receivers and two antennas are connected to one another by the circuit according to the invention.
There are expediently at least two semiconductor switching elements present in the circuit according to the invention, which elements can be switched complementarily with respect to one another, and in which case said semiconductor switching elements are directly electrically decoupled from one another. Preferably, one of the two semiconductor switching elements which are switched complementarily with respect to one another is controlled or switched by alteration of the drain and source potentials, and the other by alteration of the gate potential.
The circuit according to the invention is configured such that a negative operating or supply voltage is not present.
The circuit according to the invention can particularly advantageously be used as antenna changeover in mobile telephones or mobile radio transceivers. The circuit can preferably be used for mobile telephones or mobile radio transceivers which operate in two bands.
A further advantage of the microwave circuit arrangement according to the invention is that, in contrast to the changeover by means of conventional circuit arrangements without direct electrical decoupling of the complementarily switched semiconductor switching elements, it is possible to work with a smaller number of drive lines. It is also an advantage that the circuit manages with just a single supply voltage. Furthermore, the circuit arrangement according to the invention can be produced in a space-saving and cost-effective manner, since no coding logic is required for controlling the switching states. It is also advantageous that the circuit can be produced without complicated hybrid techniques.
A further advantage of the invention is that a microwave circuit arrangement is provided which enables a changeover between the antennas and the transmitters or receivers of the respective bands, and which requires only three lines for driving its circuit states.
A further advantage is that this microwave circuit arrangement can be realized with a low outlay on circuitry.